1. Field of the Invention
The present invention to a method of manufacturing semiconductor device, more particularly to a method of manufacturing ferroelectric random access memory device.
2. Description of the Related Art
In general, a titanium (Ti) layer is formed between a metal layer and an oxide layer as an adhesion layer for improving adhesion therebetween in manufacturing semiconductor device. It is also used to form silicide for lowering contact resistance between an active region of a transistor and a metal layer. In this case, a titanium nitride (TiN) layer is formed between the active region and the silicide layer as a diffusion barrier layer for preventing diffusion of Ti and Si. Therefore, a stacked structure of TiN/Ti in which the TiN layer is formed on the Ti layer, is formed under the metal layer when forming a metal interconnection line.
Furthermore, in case an upper electrode of a capacitor formed of a platinum (Pt) layer is connected to an active region of a transistor by a metal layer such as A1 layer and W layer in a ferroelecric memory device, the stacked structure of TiN/Ti is formed prior to forming the metal layer.
However, when forming the Pt layer as the upper electrode of the capacitor using a sputtering method, the Pt layer is conventionally grown to columnar structure and its grain boundary is not dense. As a result, Ti is diffused into a ferroelectric layer along the interface of Pt, thereby deteriorating properties of the ferroelectric layer.